1. Field of the Invention
The present invention relates to a positioning apparatus and, more particularly, to an electromagnetic probe positioning actuator.
2. Prior Art
Various types of positioning actuators are known in the prior art. One such device is known as a Sawyer linear motor that uses electromagnetic coils and tracks of ferromagnetic material having extending poles to provide linear controlled motion. Various types of these motion or positioning devices can be found in U.S. Pat. Nos. 3,351,006; 3,875,075; 4,099,106; 4,480,202; 4,761,574; 4,785,210; and 4,788,477.
One of the problems encountered with the prior art is that there was no suitable low mass device that could provide linear motion with high accelerations over a relatively long stroke. Nor was there a suitable probe that could provide a well controlled contact force, minimum impacting mass, controlled probe scrub with an object being tested, and good electrical shielding.
It is therefore an object of the present invention to overcome problems in the prior art and provide a new and improved linear positioning actuator and probe.